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[JumpThreading] ProcessBranchOnXOR(): bailout if any pred ends in indirect branch (PR46857)

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SplitBlockPredecessors() can not split blocks that have such terminators,
and in two other places we already ensure that we don't end up calling
SplitBlockPredecessors() on such blocks. Do so in one more place.

Fixes https://bugs.llvm.org/show_bug.cgi?id=46857
This commit is contained in:
Roman Lebedev 2020-07-27 15:07:51 +03:00
parent aa265a31e9
commit cd8f899c56
2 changed files with 60 additions and 0 deletions
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8
lib/Transforms/Scalar/JumpThreading.cpp
View File

@ -1859,6 +1859,14 @@ bool JumpThreadingPass::ProcessBranchOnXOR(BinaryOperator *BO) {
return true;
}
// If any of predecessors end with an indirect goto, we can't change its
// destination. Same for CallBr.
if (any_of(BlocksToFoldInto, [](BasicBlock *Pred) {
return isa<IndirectBrInst>(Pred->getTerminator()) ||
isa<CallBrInst>(Pred->getTerminator());
}))
return false;
// Try to duplicate BB into PredBB.
return DuplicateCondBranchOnPHIIntoPred(BB, BlocksToFoldInto);
}

52
test/Transforms/JumpThreading/pr46857-callbr.ll Normal file
View File

@ -0,0 +1,52 @@
; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
; RUN: opt < %s -jump-threading -S | FileCheck %s
; CHECK-ALL-LABEL: @func(
define i1 @func(i1 %arg, i32 %arg1, i1 %arg2) {
; CHECK-LABEL: @func(
; CHECK-NEXT: bb:
; CHECK-NEXT: br i1 [[ARG:%.*]], label [[BB3:%.*]], label [[BB4:%.*]]
; CHECK: bb3:
; CHECK-NEXT: [[I:%.*]] = icmp eq i32 [[ARG1:%.*]], 0
; CHECK-NEXT: br label [[BB7:%.*]]
; CHECK: bb4:
; CHECK-NEXT: callbr void asm sideeffect "", "X"(i8* blockaddress(@func, [[BB7]]))
; CHECK-NEXT: to label [[BB5:%.*]] [label %bb7]
; CHECK: bb5:
; CHECK-NEXT: br label [[BB7]]
; CHECK: bb7:
; CHECK-NEXT: [[I8:%.*]] = phi i1 [ [[I]], [[BB3]] ], [ [[ARG2:%.*]], [[BB5]] ], [ [[ARG2]], [[BB4]] ]
; CHECK-NEXT: [[I9:%.*]] = xor i1 [[I8]], [[ARG]]
; CHECK-NEXT: br i1 [[I9]], label [[BB11:%.*]], label [[BB11]]
; CHECK: bb11:
; CHECK-NEXT: ret i1 [[I9]]
;
bb:
br i1 %arg, label %bb3, label %bb4
bb3:
%i = icmp eq i32 %arg1, 0
br label %bb7
bb4:
callbr void asm sideeffect "", "X"(i8* blockaddress(@func, %bb6))
to label %bb5 [label %bb6]
bb5:
br label %bb6
bb6:
br label %bb7
bb7:
%i8 = phi i1 [ %i, %bb3 ], [ %arg2, %bb6 ]
%i9 = xor i1 %i8, %arg
br i1 %i9, label %bb11, label %bb10
bb10:
br label %bb11
bb11:
ret i1 %i9
}